In an environmentally conscious era, improvements to power consumption of electronic devices equipped with batteries or connected to an external power network are important. All electronic devices rely on energy or power to perform their useful tasks. Low power consumption is one factor that bears on the usefulness of a device. To save energy, some devices, such as telematics circuitry, may be turned off during long periods of disuse.
Varied techniques and systems exist to manage power requirements or power usage of electronic devices, such as, for example, the design of more efficient circuitry, the use of control software layers with capacity to manage power consumption by optimizing tasks, the software management of energy waste associated with standby modes, and appropriate to this disclosure, hardwired systems designed to optimize the method of operation of a device to prevent power loss when the device is not in use.
The use of power saving modes is already known. Some devices use a sleep or standby mode of operation on microprocessors or other computer processor units to switch off some functions when they are not needed. One problem with these sleep or standby modes is the action require to awaken the device. Personal laptop computers often use this technology to conserve useful battery energy, but keyboards must remain powered to allow users to touch a key to awaken the device. In these systems, to preserve software functions and maintain parts of executed memory applications, the software layer must also remain partially active while being incapable of full interaction with the user. Upon an external command from a user, such as depressing a key on a keyboard, full functionality is turned back on and interaction with the user can resume once the software layer is fully reactivated. In these systems, the microprocessor remains enabled, and though operating at a lower level, still consumes energy.
Other power saving modes are directed at changing the performance requirements of the device. For example a personal computer in a power saving mode can have the display luminosity diminish substantially to conserve energy. Memory access drives can operate more slowly, and microprocessor clocks can be slowed to operate at colder and more energy-efficient levels. These are only a handful of possible energy-saving configurations known in the art.
U.S. Pat. No. 7,315,097 assigned to Fujitsu Limited is shown in FIG. 1 as part of the prior art. This reference is directed to a device for optimizing the power consumption of a device when certain conditions are met. A manual switch is used to energize the system using a latch circuit connected to a switch placed between an AC adapter and an over-current detection system. One obvious problem of this technology is the manual interruption mechanism. This system does not truly save power unless a user uses the switch, and users may then close the device altogether. To protect the electronic device, the system uses the latch circuit and turns off the circuit when an over-current is detected. The system is designed to protect the microprocessor against over-currents and requires a proximate user to energize the device. What is needed is a power saving mode capable of managing itself independent of the location of a proximate user and independent of over-current activity.
U.S. Patent Publication No. 2008/0231121 to Yang is shown in FIG. 2 as prior art. This device is an inline cutoff system for placement in a loop to interrupt the power in a system when a certain condition occurs. This technology is directed at the recognition of recognition of normal sleep modes in systems and then uses the switch and the switch unit to permanently cut off power in the system, which then requires manual reactivation. What is needed is a built-in power saving mode that is self-awakening and also capable of management of its power down mode without the use of residual power to the microprocessor.
Unlike computer microprocessors that need to remain partly powered or where some memory attached to the microprocessor needs to keep RAM memory intact, other microprocessors and associated telematics circuitry may be used at infrequent intervals and may be placed in a powerless state for long periods of time. What is needed is a system or configuration where a microprocessor or telematics circuitry can be permanently powered down and reactivated by the powered-down microprocessor using limited power from a battery based on a predetermined wake-up variable sent by the microprocessor to the system.